Controlling of surface and humidity detecting properties of carbon films - selection of a precursor for carbonization

Semiconductor carbon films have found an application in the construction of humidity sensors. The films obtained from polyfurfuryl alcohol (PFAl) are much more sensitive towards water vapour if their surface is covered by oxygen containing functional groups. That may by easily achieved by an alkali metal modification (by means of NaOH solution) of virgin carbons. The application of other polymers for carbon film manufacturing (PVAc) revealed an opposite phenomenon. The films obtained from raw or modified PVAc despite high content of oxygen species on the surface are considerably water repellent. The water repellent properties of PVAc-originated carbon films result from the presence of -CH3 on the surface. (C) 2001 Elsevier Science B.V. All rights reserved.